Bring marinade in saucepan to boil. Reduce heat to medium-low. Whisk in butter, 1 slice at a time, allowing each to melt before adding next (do not boil). Season butter sauce to taste with pepper. Serve sauce with kebabs.

Grilling Tip

Using flat metal skewers (sold at cookware stores and supermarkets) will prevent the kebabs from sliding around as they are turned.